Feeling dirty/betrayed is an issue of forgiveness. You may have said your forgive, but if it's still a painful issue that makes you feel sick when you think about it, then forgiveness is still in the works. I may not be able to convince you of it, but once forgiveness comes, true forgiveness, you may not forget, but it doesn't hurt to remember. This I speak from personal experience, as well as experience dealing with people who have been victims of abuses. My sister was abused by my step-father, and she said the same things you are. She said she forgave, but if she ever saw him, she'd kill him. She said she forgave, but he was a {insert mean word here}. Then one day she did forgive, and now wants to take him out and say she's ok now, and she wants to tell him she forgives him.
When you look at your wife, you have to ask yourself, if you were to die today, who would cry at your funeral? These are the people who love you. And 20 years from now, can you see yourself with your wife? If not, then you have the option to divorce. But also know that I never believe anyone is 100% at fault in a relationship, so you have to determine what you did wrong before entering another relationship, and that's not an easy thing to do. We all have self-serving bias, so I suggest talking to someone and asking for an honest opinion, but someone who knows you and you respect.
I will also say that because I didn't truly forgive my wife, even though I said I did, I ended up doing some things that almost killed my wife and I. On the outside I said I forgave, because that's the 'Christian' thing to do, but on the inside I wanted to hurt her. I would look at my wife and actually picture punching her, but I'd say I forgave. Now I can see that I was deceiving myself, because I wanted to display that I was a 'Christian man'. It was only an act of God that true forgiveness came, due to the fact that I was willing to submit to God, and my wife was as well. I will now testify that God is able to heal that pain, and give you much more than you can imagine. But both must be willing to change, as one willing for another to change isn't enough. At the same time, the decision to stay or go must be made, and once it's made, stick with it. You leave a back door open for the devil when you think you are staying for her, but you may change your mind. Not only that, but there is no opportunity for trust to grow like that, and your wife will not feel secure in a marriage, and therefore you would not be fulfilling your duty to love her as Christ loved the church. If you leave, realize you have that right, but don't stay for a while for whatever reason, when in your heart you're already gone, that is using your wife.
Again, I know it's not a nice thing to go through, but we must always abide by kingdom principles in all situations. If you do not divorce, you have to love her like Christ loved the church. If you do, then you still must forgive, and are free to move on.
